Humans perceive depth principally through the effect of parallax, which requires binocular vision. Most conventional techniques for photographically capturing depth information from many points in a three dimensional scene involve stereoscopic recording equipment. A stereoscopic recording apparatus generally utilizes two cameras which are offset in a direction perpendicular to the direction of view. The resultant images can be viewed by a person with two functional eyes to extract depth information from the images. Automated means are used in the cartographic field for extracting depth information from stereoscopic images.
A stereoscopic recording apparatus requires that the two cameras be aligned to a high degree. This requirement makes the cost of constructing and maintaining a stereoscopic apparatus high. Further, the automated methods available for retrieving depth information from stereoscopic images suffer from high computational cost and generally low accuracy. Because some points in one stereoscopic image are often hidden in the other stereoscopic image, some error is probably inevitable in the automatic retrieval of depth information from stereoscopic images.
A typical non-stereoscopic technique for recording depth information over a three dimensional scene is confocal microscopy. In confocal microscopy a single photodetector is situated behind a pinhole in an opaque screen. An objective lens focuses light from an illuminated point onto the pinhole, and the screen masks out any non-focused light. The illuminated point is generally illuminated by an intense, focused light source, such as a laser. The illuminating light source and the pinhole must be scanned over a microscopic specimen, either one point at a time or in a series of lines. Depth information can then be extracted from the data recorded from the photodetector. Such a system is too complex and expensive for typical microscopy, and is not useful for macroscopic range detection.
What is needed is a system for determining depth information in a given three dimensional scene from information entering a single lens system. The system should allow for the recordation of depth information of either microscopic or macroscopic scenes, and should not require the use of a scanning light source.